Cleared for Mach 2 after departure, this supersonic jet of the future
would yaw 90 degrees and put a new set of wings into the wind. The
brainchild of Ge-Chen Zha of the University of Miami,
the "supersonic, bi-directional flying wing" recently landed a $100,000
NASA grant to continue development of a concept that could cut the New
York to Tokyo travel time to four hours — and perhaps significantly faster
than that, Zha said.

Zha, who is collaborating with peers from Florida State University on
the concept design, said "there’s no limit" to the potential speed the
star-shaped airframe could allow, with single-stage to orbit and
hypersonic speeds (above Mach 5) well within the realm of possibility.
That speed would be delivered with low drag, low fuel consumption, and
no sonic boom — the noise of which has stalled previous attempts to create
supersonic travel routes over populated areas.

While the concept design is sized as a business jet, Zha said there should be little difficulty scaling it up to airline size.

Zha, who has followed recent difficulties that the U.S. Air Force has had launching a missile to Mach 5,
said propulsion and aerodynamic challenges must be overcome, and many
of those challenges still are not well-understood. It may take decades
to solve some of the problems faced by all hypersonic designs.

Still, Zha said, the bi-directional design "does provide a very
promising configuration." By combining the virtues of two very different
wings, the concept sidesteps — literally — one of the major challenges
posed by high-speed flight: Wings that provide the lift required for
low-speed maneuvering, including takeoff and landing, produce too much
drag to be efficient at supersonic speeds. An ideal high-speed wing, on
the other hand, would be downright dangerous in the traffic pattern.

Computer models predict the bi-directional aircraft would perform well
both at low speeds — taking off and landing from airports — and at high
speed. Making the 90-degree rotation that exchanges wings would be a
complicated maneuver, controlled by a computer to span the transition
over several seconds and make the change barely perceptible to
passengers and crew in flight. As engines rotate and control forces
transfer to different sets of control surfaces, passengers would feel an
acceleration of just 0.2-Gs as the aircraft rotated on its axis, Zha
said, noting the concept has been extensively modeled in digital form.
Long, thick wings designed for low-speed flight would rotate to the
longitudinal axis, and shorter, thinner wings better suited for
efficient high-speed flight would provide lift at supersonic speeds — and
beyond.

The funding from NASA’s Innovative Advanced Conceptsgrant program is just enough to begin wind tunnel testing, Zha said.
Design refinement and mission analysis will also be paid for with the
one-year grant; Zha hopes to secure a Phase II grant from the same NASA
program that would bring another $500,000, but that is still a small
amount relative to what will be required to build a prototype. Zha said
private investment could accelerate the process, and make a certified
aircraft available in as little as a decade.

"If we have all the money we need, probably 10 years could be doable," Zha said.

A more realistic estimate, however, puts this new design in the air
in about 20 years, Zha said, noting that the research team is eager to
work with private investors interested in speeding things up.